Ki vette feleségül Margareta of Opava-Ratibor-t?

Casimir I of Oświęcim (Polish: Kazimierz I Oświęcimski) (1396 – 7 April 1434) was a Duke of Oświęcim from 1406 (under regency until 1414) until his death in 1434, ruler over Toszek (from 1414 to 1434) and Strzelin (during 1416–1427).

He was the only child of Duke Przemysław of Oświęcim by his unknown wife.

Siemowit V of Rawa was a Polish prince of the House of Piast from the Masovian branch. He ruled as Duke of Rawa Mazowiecka, Płock, Sochaczew, Gostynin, Płońsk, Wizna, and Belz from 1426 to 1434 with his brothers, and after the 1434 division of their inheritance, solely over Rawa Mazowiecka, Gostynin, and Sochaczew.